Solution
The reaction below represents the oxidation reaction which occurs at the anode or negative terminal
The reaction below represents the reduction reaction which occurs at the cathode or positive terminal
Adding the two reactions above will give the overall reaction occurring as the cell discharges.
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Solution
As the battery is heated the ammonia molecules gain kinetic energy and migrate away from the cathode. This allows contact between the paste and the cathode once more and overall reaction can proceed to its conclusion.
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The chemistry behind the modern day battery
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The dry cell |
Often the ammonia produced from the above reaction builds up at the cathode. This tends to insulate the cathode and prevent any electron flow. A few more seconds of use can be had from the battery if it is heated slightly. Why is heating effective? Solution |
| The dry cell is used in torches, portable radios, calculators and many more portable electronic items. The word "dry" is very misleading for without water the dry cell could not work. The oxidation half reaction is given below. | |
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The reduction
reaction is somewhat complex but it involves the reduction of manganese(IV)oxide
to manganese(II) ion. At the cathode the following reaction takes place and represents the reduction reaction. |
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| The hydrogen produced is quickly oxidised to water according to the following equation. | |
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| Which of the above reactions occurs at the +ve electrode of the dry cell and which one occurs at the -ve electrode? | |
| Write the overall
reaction that occurs in the dry cell Solution |
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Continue
with the lead acid accumulator |
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